Field of the Invention
The present invention relates to a current detection circuit, and particularly to a current detection circuit which detects that a prescribed current flows into a current measuring resistor.
Background Art
A circuit diagram of a related art current detection circuit 200 is illustrated in FIG. 2.
The related art current detection circuit 200 is equipped with a current inflow terminal 203, a reference terminal 202, a current measuring resistor 241, and a current detection part 251.
The current detection part 251 is comprised of a voltage input terminal 204, a reference terminal voltage input terminal 206, a reference voltage circuit 20, a voltage comparison circuit 261, and an output terminal 205.
The current inflow terminal 203 and the reference terminal 202 are connected to each other through the current measuring resistor 241 and further connected to the voltage input terminal 204 and the reference terminal voltage input terminal 206 respectively.
The reference voltage circuit 20 is provided between the reference terminal voltage input terminal 206 and a minus input terminal of the voltage comparison circuit 261 and supplies a reference voltage Vref based on a voltage of the reference terminal voltage input terminal 206 to the minus input terminal of the voltage comparison circuit 261. The voltage input terminal 204 is connected to a plus input terminal of the voltage comparison circuit 261, and the output of the voltage comparison circuit 261 is connected to the output terminal 205.
The relate art current detection circuit 200 configured as described above is operated as follows.
With a measuring current flowing from the current inflow terminal 203 to the reference terminal 202 through the current measuring resistor 241, a voltage generated at one end of the current measuring resistor 241 is inputted to the voltage input terminal 204. This input voltage and the reference voltage Vref are compared by the voltage comparison circuit 261.
Since the voltage of the voltage input terminal 204 exceeds the reference voltage Vref when the measuring current reaches a detection current value, the output of the voltage comparison circuit 261 becomes a high level so that a high-level current detection signal is outputted from the output terminal 205 (refer to, for example, FIG. 2 of Patent Document 1).
[Patent Document 1] Japanese Patent Application Laid-Open No. 2005-241463
In the above-described related art current detection circuit 200, since the voltage comparison circuit 261 is normally configured to include at least a differential amplifier circuit and a buffer circuit, current consumption of the voltage comparison circuit 261 is large.